1. Technical Field
This invention relates generally to vehicle navigation systems and, more particularly, to using special routes in a vehicle navigation system.
2. Related Art
Vehicle navigation systems are becoming increasingly popular in the automobile industry. A typical vehicle navigation system includes a global positioning system (“GPS”) receiver that is mounted somewhere on the vehicle. The GPS receiver is capable of communicating with a satellite-based global positioning system or other localized positioning systems. The GPS receiver obtains position information that is converted into some form of display for the vehicle operator indicating the position of the vehicle relative to previously determined reference points or other known landmarks on a given map database.
The typical vehicle navigation system also includes a digital map database module that includes digitized map information that can be processed by a navigation computer designed to handle map-related functions. A map matching module is used to match the position or trajectory measured by a positioning module to a position associated with a location or route on a map provided from the digital map database. The positioning module receives its information from the GPS receiver.
A route planning module is also typically included that is used to help vehicle drivers plan a route prior to, or during, a trip. One commonly used technique is to find a minimum-travel-cost route, which is designed to minimize the amount of distance traveled and costs associated with reaching a predetermined destination. Other techniques exist that integrate the time one needs if using dedicated roads or may use information about traffic conditions on the route to calculate a route that avoids the traffic condition. A route guidance module is also included that is used to guide the driver along the route generated by the route planning module. Guidance can be given, either before the trip, or in real time while en-route. The real time or en-route guidance is typically generated using optical driver recommendations and/or acoustic driver recommendations.
The typical vehicle navigation system also includes a human-machine interface module that provides users with a way to interact with the location and navigation computer and devices. A visual display is typically used to convert signals into a visual image in real time for direct interpretation by the user. As such, displays are used to provide the optical driver recommendations. The display itself is typically an electro-optical device such as a liquid crystal display (“LCD”), a cathode-ray tube (“CRT”) display, an electroluminescent display (“ELD”), a heads-up display (“HUD”), a plasma display panel (“PDP”), a vacuum fluorescent display (“VFD”), or a touch-screen display.
The human-machine interface module may also include a voice-based interface that allows the user to interact with vehicle navigation system. The acoustic driver recommendations are provided using the voice-based interface. Speech is the most common interface that is used for delivering acoustic driver recommendations because it provides a natural interface that does not distract the driver from operating the vehicle and/or paying attention to the roadway. As such, information provided through acoustic driver recommendations may be safer because it allows the vehicle operator to concentrate on the task of driving.
During operation, the user may enter a trip destination into the vehicle navigation system because the vehicle navigation system may calculate a route based on the current position of the vehicle. The vehicle navigation system will then calculate an optimal route from the origin to the destination and display the optimal route to the user on a display. The user of the vehicle navigation system does not have any influence over the choice of the route to be selected or calculated by the navigation system to the destination. The user could choose not to follow the selected route. However, the user may want to vary the selected route based on user concerns or needs not taken into consideration by the navigation system.
Several types of vehicles may not be allowed to travel on certain routes calculated by the vehicle navigation system. For example, wide-body trucks may not be able to travel on narrow roads or inner city streets. Heavy transport vehicles or trucks may not be able to traverse over particular bridges or roads that cannot support the weight of the load being carried by the truck. In addition, trucks that are taller or carrying a tall load may not be able to fit underneath bridges along a roadway. As such, a need exists for a vehicle navigation system that will allow the user of the vehicle to have some influence over the route that is calculated to the destination based on predetermined characteristics.